Arizona Sen. John McCain is the nation’s foremost neoconservative hawk. In a recent Wall Street Journal column, he advocated an aggressive US military engagement in the Syrian civil war. Its failure is also highly likely. And it would take risks and incur costs highly disproportionate to true US interests in the outcome.

According to McCain, the United States should ground Bashar Assad’s air force by destroying his planes if they fly. McCain says we should do this with “coalition partners.” But so long as Russia is in the picture, no other country will be joining in that mission.

And what about Russia? Here, McCain is uncharacteristically oblique. He says that “if Russia continues its indiscriminate bombing, we should make clear that we will take steps to hold its aircraft at greater risk.”

What in the world does that mean? Here’s an unblinking translation: We should threaten Russia with war in Syria.

McCain also says that “we must create safe zones for Syrian civilians and do what is necessary to protect them against violations by Mr. Assad, Mr. Putin and extremist forces.” That would require a large number of US ground forces prepared to fight in Syria’s civil war.

And McCain wants US taxpayers to arm “vetted Syrian opposition groups that are fighting the regime.”

Let’s pause to take a breath and try to gain some perspective.

Who governs Syria is more important to Russia and Iran than it is to the United States. Assad provides Russia its only naval port in the Mediterranean. Iran has a stake in Assad as an ally in the larger Shia-Sunni contest for regional influence.

Who governs Syria is of little strategic interest to the United States, in and of itself. So, Russia and Iran will always be willing to take the fight deeper and longer than the United States. They won’t be cowed by a US military bluff.

A better approach would be for the United States to get out of the way in Syria.

The United States has tried to micromanage the Syrian opposition, witnessed by McCain’s reference to “vetted” groups.

In reality, however, all the opposition forces are Sunni Islamists of some flavor or another. They aren’t fighting for democratic governance or free markets. They are fighting to oust a Shiite dictatorship in a Sunni-majority country.

There are jihadists among them. But the other reality is that adversity on the battlefield has caused the rebel forces to largely unite. The opportunity for hygienic support for “vetted” rebels, if it ever existed, has passed.

Saudi Arabia,Turkey and Qatar want to see Assad gone. They have wanted to do more to arm the rebels and aren’t as fastidious as the United States about who gets the aid, as long as it is aimed at Assad. The United States has held them back.

If the United States got out of the way, Assad’s regional enemies would see to it that he faces a more robust opposition. That wouldn’t bring peace. In fact, it would presumably make at least the ground war more intense.

However, it would increase the cost of the war to Russia and Iran. Which might create the preconditions for discussions of a peace settlement that basically partitions the country.

McCain sees a US strategic interest in combating what he considers “an anti-American alliance of Russia and Iran.” But the national interests of the United States, Russia and Iran aren’t inherently inimical in the region.

The true, current strategic interest of the United States in the region is reducing the writ and capabilities of Islamic State. Focusing on that means accepting some strange, at least de facto alliances. Shiite militias with Iranian ties are fighting both for Assad and against Islamic State.

The Obama administration has been an inept failure in Syria. That, however, isn’t a reason for the United States to become a combatant in Syria’s civil war.